Population growth and mass production of brackish water cladoceran Eurycercus beringi sp. nov. under different diet and salinity regime, and its role in P. indicus larval rearing

Abstract

The growth performance and mass production of Eurycercus beringi sp. nov., comes under cladocera isolated from Adyar creek, Chennai fed with different diets includes Chlorella sp, Nannochloropsis sp, Chaetoceros sp, Thalassiosira sp, Tetraselmis sp, Dunaliella sp and Isochrysis sp, rice bran and baker’s yeast as monospecific and mixed diets (1:1) have been investigated. The species reproduce parthenogenetically attained a size range of 300- 1098μm and tolerate salinity range of 3–35‰ with fecundity range of 2–7 numbers with minimum maturation period of 3–6 days depending on quality of feed with minimum aeration. Salinity found to play a significant role in survival with maximum survival at 25 ‰. There is a significant difference (p<0.05) in survival at lower and higher salinity. The highest fecundity was observed in the treatment fed with Chlorella and Nannochloropsis sp followed by Chlorella and Thalassiosira sp (1-3×105 cells/ml) i.e. 8 and 7 number of individual/broodstock respectively where as the species attained maturity within 3 days in the treatment fed with Chlorella sp followed by combination of Chlorella and Chaetoceros sp (4 days) and Chlorella and Thalassiosira sp as monospecific diet (4 days each). Mass culture of E. beringi sp. nov. at 100 nos/L was carried out using microalgae, rice bran and baker’s yeast revealed a maximum density 5887 ± 109 nos/L recorded at 30 ‰ within 7 days when fed with mixed diets of Chlorella and Nannochloropsis sp followed by rice bran with baker’s yeast (4586 ± 167 nos/L). Partial replacement of Artemia nauplii with E. beringi sp. nov. (1:1) with highest survival (65 ± 3 %) during early post larval stages of Penaeus indicus revealed its potential to use as live feed in larval rearing. The study highlighted the scope of E. beringi sp. nov. to use as live feed during the larval rearing of brackishwater finfish and shellfishes.